US2733317A - Pl tayi or - Google Patents

Description

9 19555 P. L. TAYLQR 2333,31?

INTEIRRUPTER EMPLOYING AXIALLY ARRANGED BARRIER PLATES FOR INTERRUPTING SERIES ARCS Filed April 20, 1955 United States Patent INTERRUPTER EMPLOYING RANGED BARRIER PLATES FOR INTER- RUPTING SERIES ARCS Philip L. Taylor, Abington, Mass, Chalmers Manufacturing Company,

AXIALLY AR- assignor to Allis- Milwaukee, Wis.

Application April 20, 1953, Serial No. 349,688 8 Claims. (Cl. 200-150) system, and the type of the circuit breaker. such a capacitance load, interruption at the first current zero in the arc of the leading current is readily effected at a relatively small contact separation. in one-half cycle zero, the voltage of the source has reversed to its crest value, and approximately double this voltage appears across the circuit breaker contacts as a circuit recovery voltage. Whether or not restriking of the arc occurs depends on several factors, such as the type of the circuit breaker, including the speed and the magnitude of the separation of its contacts, the magnitude of the circuit recovery voltage, and the leading kva. of the load.

These circuit conditions are difficult it not impossible to control. Therefore, restriking in most breakers must In isolating which an arc and separa- A means is provided for causing the first pair of contacts to draw an are before the second pair of contacts draws an arc in a circuit breaker interrupting operation. An arc extinguishing device comprising a plurality of barrier plates is arranged adjacent the first pair of contacts and defines a passageway extending through the barrier plates. Means are provided for guiding a How of fluid across the passageway and between the barrier plates of the arc extinguishing device during the interrupting operation for cooling and extinguishing the arc.

It is, therefore, one object of the present invention to provide a new and improved circuit interrupter arranged to sequentially draw at least two serially connected arcs in which the first arc is subjected to unionized arc extinguishing fluid forcibly impelled into the arcing region at one or more points along the arc.

jected to un-ionized pelled into the arcing the arcs.

A further object of this invention is to provide a new and improved circuit breaker to elongate a pair of serially connected arcs in which each arc is individually subjected to llll-iOIllZ6d arc extinguishing fluid forcibly impelled into the arcing regions.

A still further object of this invention is to provide a new and improved circuit breaker in which low current arcs are subjected to a plurality of inwardly flowing streams of fluid under pressure which converge on the arc to rapidly cool and extinguish it.

Objects and advantages other forth will be when read in ings in which:

Fig. 1 is an elevational view partly in section of a circuit interrupter embodying the invention and shown in circuit closed position;

Fig. 2 is an enlarged sectional view through one of the interrupting devices shown in Fig. 1 and embodying the present invention; and

Fig. 3 is a sectional view of the circuit breaker structure shown in Fig. 2 taken along the line IH-IIL than those above set following description voltage type such as that used in power transmission systems. Unit 1 is suspended from one line terminal of the circuit interrupter in a suitable 3 such as oil. A conducting bridging bar 3 serves to connect electrically the are extinguishing unit 1 with an identical unit 4 in a manner well known in the art. Supported on a cover 5 of the tank 2 are a pair or" terextinguishing unit 1. Clamped to the lower end of a terminal bushing 6 is a conductive housing 11 which forms a conductive path between it generating contact 16.

contact 14 secured to the extremity of the cross bar 3 Contact 14 is arranged in a pressure chamber 42 Contact 13 comprises two contact engaging surfaces Contact 16 cooperates with faces to produce 14 cooperates with faces to produce A plurality of 15 rest against the upper end of rod shaped contact 16. Current is transferred from housing 11 to contact 16 through rocking finger contacts 15. This arrangement dispenses with 1, as shown in Figs. 1 and 2, the electric intermediate contact 13, movable interrupting contact 14, conducting cross bar 3, movable interrupting contact 14', and the right hand are extinguishing unit 4 as in housing 11 to the terminal stud (not shown) in bushing 7.

Contact 16 is actuated by a lever 17 having an oblong hole 18 in one end thereof and adapted to be rocked about a stud 19. A pin 1% in rod 16 engages oblong hole 13 in lever 17. A cradle 2% is journaled to lever 17 by means of a pin 21 and biased downward by a spring 22. Cradle 2i supports a rod 23 for the operation of a piston pump 1 12. Cradle is adapted to be operated by an insulating operating tube or rod 25 which in turn is operated by the cross bar 3 of the circuit breaker. When cross bar 3 and operating rod 25 are raised or lowered, the cradle 29 is simultaneously raised or lowered and rocks about pin 21 relative to lever 17 simultaneously with its raising or lowering movement. The circuit breaker unit 1 may employ contacts 16 and 13 alone or in combination with spring actuated oil pump 12 for the interruption of line charging currents and such low value of inductive currents as not effectively interrupted by other types or" devices.

A valve disk 27 is loosely mounted on rod 23 and biased against the piston 24 of pump 12 by a spring 28. Spring 28 is disposed between the valve disk 27 and a flange 29 secured to housing 11. The piston 24 is provided with a plurality of apertures 36 which form a passageway for oil flow under certain conditions between the upper and lower portions of the housing through piston 24. The apertures are controlled by disk 27.

During a circuit closing operation of the interrupter, the bridging contact member. or bar 3 forces the operating rod 25 upward. Operating rod 25 in its upward movement rotates arcing contact lever 17 counterclockwise to cause contact 16 to engage the contact surfaces of the fixed contact 13. Rod 25 in its upward movement to closed circuit position pushes rod 23 upward against the biasing action of the spring biased piston 24 of pump 12.

The arc interrupting unit 1 utilizes two groups of barrier plate assemblies and 36 of suitably shaped insulating plates which form part of the walls of the paths through which the arcs produced by contacts 16, 13 and 14 are drawn.

Each interrupting unit is provided with two parallel cylindrical resistor assemblies 45. The upper end of each resistor assembly is conductively connected to an electrostatic shield 46. Shield 46 is conductively connected to housing 11 which in turn is conductively connected to the lower terminal end of the breaker bushing 6. The lower end of each resistor assembly 45 is conductively con nected to the lower electrostatic shield 47. Shield 47 is conductively connected to an arcing electrode comprising a disk like member 48 through a conductive circuit comprising bolts 49, plate 50, bolts 51 and ring support 52.

The lower end of the arc interrupting blast chamber 42 comprises an insulating nozzle 55 forming a fluid opening 56. The. arcing electrode 43 is secured within chamber 42 between the lower end of the barrier plate assembly 36 and the blast opening 56.

When it is desired to open the electric circuit passing through the interrupter, or when overload conditions exist in the electric circuit controlled by the interrupter suitable operating mechanism (not shown) moves the insulating lift rod 8 to result in a downward movementof the conducting cross bar 3 and the movable contacts 14, 14'.

The downward movement of cross bar 3 causes insu' lating operating rod 25 to rotate lever 1'7 clockwise about the pivot stud 19 to drawn an are between contacts 16 and 13. Substantially simultaneously therewith or with a slight delay the movable contact 14 separates from the intermediate or fixed contact 13- to draw an are between contacts 13' and 14. The downward movement of operating rod 25 causes'the downward movement of piston 24 to move the oil within the pump cylinder 26. The oil, now under pressure within the pumpcylinder 26lflows. un-

der. pressure out of the cylinder 26. through passageway 37,.

through the barrier plate stack 35 transversely of the longitudinal axis of the arc extinguishing unit 1, through the passageway 33 into chamber 39 and through orifice 40 to the inside of tank 2.

As shown in Fig. 2, an aperture may be provided in plate 61 which separates the upper grid assembly 35 from the chamber 42 and particularly from the lower grid assembly 36. This aperture 66 may be omitted if it is desired to substantially completely isolate the upper cham' ber 41 from the lower chamber if aperture 6% is provided in plate 61 then the are drawn between the contacts 16 and 1.3 may be called a pressure generating arc and the are drawn between contacts 13 and 14 an interrupting arc. With aperture 60 in plate 61, piston 24 causes a first flow of fluid under pressure through the passageway 37, through the passageway 62 extending across the barrier plates of assembly 35. The passageway 62 extending through the barrier plates also extends across the passageway 63 extending through the barrier plates longitudinally of the axis of the inter rupter. As noted, the passageway 62 comprises aligned inlet and outlet portions wherein the inlet and outlet portions are arranged to extend within passageway 63 on opposite sides thereof. Piston 24 also causes a second flow offluid under pressure through passageway 37, aperture 6G in plate 61, chamber 42 and into the barrier plate assembly 36. The first blast of fluid under pressure cools and extinguishes the pressure generating arc and the second blast of fluid under pressure cools and extinguishes the interrupting arc.

During the interruption of. low currents, the operating rod 25 moves downwardly at the same speed as the cross bar 3 to result in the lever 17 rotating clockwise about stud 19 to draw an are between contacts 16 and 13. The rod 23 and piston 24 follow the downward movement of operating rod 25. Valve disk 27 closes apertures 30 and moves the oil in cylinder 26 into passageway 37. This action occurs during the interruption of low currents.

During the interruption of high current arcs, the pressure created by the are drawn between contacts 16 and 13 may prevent the downward movement of the piston 24 and this, in turn, halts the downward movement of the rod 23. The cradle 29 then separates from rod 23.

When the pressure subsides within the barrier plate assembly 35 oil under pressure within housing 26 flows out through barrier plate assembly 35 to llush the region where the arc occurred between contacts 16 and 13. This scavenging action raises the dielectric strength of the oil in the barrier plate assembly 35 and prevents restriking between contacts 16 and 13 which would prolong the arcing time of the interrupter. It also prevents premature breakdown of the contact gap during and immediately following closing operation. The grid assembly 35 is particularly useful in circuit breakers used to isolate a capacitive load of such capacitance and voltage that the voltage gradient across the arc interrupting contacts of the circuit breaker exceeds the dielectric strength between these contacts.

For efficient circuit breaker operation it is desirable to provide an arc extinguishing device adiacent the pressure generating-arc as well as the interrupting arc.

The downward. movement of contact 14 draws an arc in the barrier plate stack assembly 36 between contact 14 and the fixed contact 13. The are drawn between contacts 13 and 14 breaks down a portion of the arc extinguishing liquid which surrounds the arc saturating the barrier plate assembly 36. The barrier plate assembly 36 may be of the type shown and claimed in U. S. Patent No. 2,467,542, P. L. Taylor, April 19, 1949. This type of barrier plate assembly provides helical passages which produce a helical flow of liquid through the barrier plates and. the contact passageway 32 formed therein.

Most of the disks shown in the barrier plate assembly 36 have three cut out sections 64, which sections are aligned in the stack to form longitudinal. venting passages 65 As the contact passageway 32 extends downward through the barrier plate assembly 36, vents 66 from the contact passageway 32 to the longitudinal venting passages 65 are provided at intervals as shown in Fig. 3. Venting passages 65 communicate with a plurality of exhaust ports 67 provided in the insulating shell 68 forming a part of the structure of unit 1.

While the circuit breaker is opening the arcing surface 33 of the movable contact 14 passes the arcing electrode 48 before passing through nozzle 55. Part of contact 14 moves through the nozzle during interruption of the power are. Immediately after momentary interruption at a current zero the returning voltage between contacts 13 and 14 cause current to flow through the resistor assembly 45 because the voltage breaks down the gap at one or more points on the surface of arcing electrode 48 (due to the short gap between the electrode 48 and the body of contact 14 as compared with the main interrupting gap between surface 33 and contact 13). The resistor assembly 45 is thereby inserted in series with the power circuit through an auxiliary are so that the resistance circuit now shunts the contacts 14, 16 and 137 The magnitude of the arc current is correspondingly decreased by the resistance and the difficulty of completely interrupting the current is greatly diminished, particularly in the case of circuits having high rates of increase of the recovery voltage and also in the case of capacitance switching. The ohmic value of the resistance 5 depends on the characteristics of the circuit to be controlled.

When the comparatively weak are current through the resistor is finally extinguished by the cooling effect of the oil, further downward movement of contact 14 serves to increase the oil gap for isolating the contacts from each other so that there is no danger of flashover or restriking of the arc.

Thus, an efficient, simple and compact interrupting unit is provided that occupies practically no more space within the oil tank than conventional interrupting chambers and that is easy to inspect or repair. The resistor unit can be readily removed from the breaker and replaced independently of the chamber and the contacts therein so that complete disassembly of the chamber construction is unnecessary.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

it is claimed and desired to secure by Letters Patent:

1. In a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, a stationary contact arranged to extend within both of said chambers and comprising a contact engaging surface in each chamber, a first movable contact cooperating with said contact engaging surface in said first chamber to produce a pressure generating arc, a second movable contact cooperable with said contact engaging surface in said second chamber to sequentially produce an interrupting are, a first arc extinguishing device arranged in said first chamber and comprising a plurality of barrier plates arranged transversely of said pressure generating are, said first device defining a first passageway extending from said one contact engaging surface through said barrier plates and a second passageway extending through said barrier plates transversely of said first passageway, said second passageway comprising an inlet portion issuing into said first passageway on one side thereof and aligned with an outlet portion issuing from said first passageway on the other side thereof, means for moving said first movable contact through said first passageway of said first device to ignite and extend said pressure gen erating arc, a piston operatively connected to said first movable contact and movable therewith for causing a flow of fluid through said second passageway and across said first passageway of said first device to cool and extinguish said pressure generating arc, means for moving said second movable contact to ignite said interrupting are after ignition of said pressure generating arc and for extending said interrupting arc, and a second arc extinguishing device arranged in said second chamber and comprising a plurality of barrier plates arranged transversely of said interrupting arc to cool and extinguish said interrupting arc.

2. In a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, means separating said first chamber from said second chamber to prevent the flow of said fiuid therebetween, a stationary contact arranged to extend within both of said chambers and comprising a contact engaging surface in each chamber, a first movable contact cooperating with said contact engaging surface in said first chamher to produce a first arc, a second movable contact cooperable with said contact engaging surface in said second chamber to produce a second arc, a first are extinguishing device arranged in said first chamber and comprising a plurality of barrier plates arranged transversely of said first are, said first device defining a first passageway extending along the longitudinal axis of said interrupter from said one contact engaging surface through said barrier plates and a second passageway comprising aligned inlet and outlet portions extending through said barrier plates transversely of said first passageway, said inlet and outlet portions being arranged on opposite sides of said first passageway and each extending into said first passageway, said second passageway comprising an inlet portion issuing into said first passageway aligned with an outlet portion issuing from said first passageway, means for moving said first movable contact axially through said first passageway of said first device to ignite and extend said first are, a piston operatively connected to said first movable contact and movable therewith for causing a flow of fiuid through said second passageway and across said first passageway of said first device to cool and extinguish said first are, means for moving said second movable contact to ignite said second are after ignition of said first arc and for extending said second arc, and a second arc extinguishing device arranged in said second chamber and comprising a plurality of barrier plates arranged transversely of said second arc to cool and extinguish said second are.

3. In a circuit interrupter immersed in are extinguishing fluid, a stationary contact comprising two contact engaging surfaces, a first movable contact cooperating with one of said contact engaging surfaces to produce a first arc, a second movable contact cooperating with the other of said contact engaging surfaces to produce a second are, a first arc extinguishing device comprising a plurality of parallelly arranged barrier plates, said first device defining a first passageway extending from said one contact engaging surface through said barrier plates and a second passageway comprising aligned inlet and outlet portions extending through said barrier plates transversely of said first passageway, said inlet and outlet portions being arranged on opposite sides of said first passageway and each extending into said first passageway, means for moving said first movable contact through said first passageway of said first device to ignite and extend said first are, a piston operatively connected to said first contact for causing a flow of fluid through said second passageway of said first device to cool and extinguish said first are, a second arc extinguishing device comprising a plurality of parallelly arranged barrier plates defining a third passageway extending from said other contact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said third passageway to ignite said second are after ignition of said first are and to 7 extend said second arc, said second devicercoolinggandn extinguishing said second arc.

4. In a circuit interrupter-immersedginqarc extinguish; ing fluid, a stationary contact .comprising two. contact engaging surfaces, ar-firstrmovable-contact cooperating withrone of, said contact engaging 'surfacesto, produce a pressure generating arc, a second movable contact cooperating with the other of said contact engagingsurfaces to produce an interruptingrarc, a first arcrextinguishing device comprising a plurality of parallelly arranged barrier plates, saidfirst. device-defining a first passageway extending from said, one contact engaging surface along the longitudinal axis of said interrupter, and a second passageway comprising aligned inlet and outlet portions extending throughsaid barrier plates transversely of said first passageway; said inlet .andoutlet portions being arranged on opposite sides of said first passageway and each extending intosaid first passageway, means for moving said first, movable contactaxially through said first passageway of said first device to. ignite and ext-end said pressure generating are, a piston operatively connected to said first contact for causing a flow of fiuid through said second passageway of said. first device to cool and extinguish saidpressure generatingv are, a second arc extinguishing device comprising a plurality of parallelly arranged barrier plates defining a third passageway extending from said othercontact engaging surface through said barrier plates of said second device, and means for moving said second movable contact through said third passageway to ignite .said second are after ignition of said first arc and to extend said second are, said second device cooling and extinguishing said interrupting are.

5. in a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, a means separating said first chamber from said second chamber to prevent the flow of said fiuid'therebetween, a first pair of contacts arranged within said first chamber, a second pair of contacts arranged within said second chamber, a first arc extinguishing device arranged in said first chamber and comprising a plurality of barrier plates arranged transversely of the longitudinal axis of said interrupter, said first device defining a first passageway extending along the longitudinal axis of said interrupter, and a second passageway comprising aligned inletand outlet portions extending through said barrier plates transversely of said first passageway, saidrinlet and outlet portions being arranged on opposite sides of said first passageway and each extending into said first passageway, means for separating said first pair of contacts and for moving one of said first pair of contacts. axially through said first passageway of saidfirst device-to ignite and extend a first arc, a piston operatively connected to said first movable contact and movable therewith for causing a flow of fluid through said second passageway across said first passageway of said first device to cool and extinguish said first are, means for separating said second pair of contacts to draw a second arc,. a second arc extinguishing device arranged in said second chamber and comprising a plurality of barrier plates arranged transversely of said second arc to cool and extinguish said second arc.

6. In a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, means for separating said first chamber from'said second chamber, said separating means being provided with an aperture for controlling the flow of said fluid between said first and second chambers, afirst pair of contacts arranged within said first chamber, a second pair of contacts arranged within said second chamber, a first arc extinguishing device arranged in ,saidfirst chamber and comprising a plurality of barrier platesarranged.transversely of the longitudinal axis ofsaid interrupter, said first device defininga first passageway-extending along. the, longitudinal axisgof saidinterrupter, and arsecondz."

passageway comprisingalignedlinlet and outlet portions extendingth'roughzsaid barrier plates transversely of said firstpassageway, said inlet and outlet portions being arranged on opposite sides of said first passageway and each extending intosaid first passageway, means for separatingsaid first'pair of contacts and for moving one or" said first pair of contacts axially through said first passageway of said first device to extend a first are, means for separating said second pair of contacts to draw a second arc, a second arc extinguishing device arranged in said second chamber and comprising a plurality of barrier plates arranged transversely of said interrupting arc, and a piston operatively connected to said first movable contact andmovabletherewith for causing a first flow of fluid through said second passageway across said first passageway of said first device to cool and extinguish said first arc and for causing a second fiow or" fluid through said second arc to cool and extinguish said second are.

7. In a circuit interrupter immersed in arc extinguishing fiuid, a first arcing chamber, a second arcing chamber,

meansseparating said firstcharnber from said second chamber to prevent the flow of said fluid therebetween, a stationary contact arranged to extend within both of said chambers and comprising a contact engaging surface in each chamber, a first movable contact cooperating with said contact engaging surface in said first chamber to produce afirst arc, a movable contact cooperable with said contact engaging surface in said second chamber to produce a second arc, a first arc extinguishing device arranged in said first chamber and comprising a plurality ofbarrier plates arranged transversely of said first arc, said first device defining a first passageway extending along the longitudinal axis ofsaid interrupter, and a second passageway comprising aligned inlet and outlet portions extending through said barrier plates transversely of said passageway, said inlet and outlet portions being arrange on opposite sides of said first passageway and each extending into said first passageway, means for moving one of said. first pair of contacts axially through said first passageway of said first device to extend said first are, a piston movable with said first movable contact for causing a flow of fluid through said second passageway across said first passageway of said first device to cool and extinguish saidfirst arc, a second arc extinguishing device arrangedin said second chamber and comprising a plurality of barrier plates arranged transversely of said interrupting arc to cool and extinguish said second arc.

8. In a circuit interrupter immersed in arc extinguishing fluid, a first arcing chamber, a second arcing chamber, means for separating said first chamber from said second chamber, said separating means being provided with an aperture for controlling the flow of said fluid between said first chamber and said second chamber, a stationary contact arranged to extend within both of said chambers and comprising a contact engaging surface in each chamber, a first movable contact cooperating with said contact engaging surface in said first chamber to produce a first arc, a movable contact cooperable with said contact engaging surface in said second chamber to produce a second are, a first arc extinguishing device arranged in said first chamber and comprising a plurality of barrier plates arranged transversely of said first arc, said first device defining a first passageway extending along the longitudinal axis of said interrupter, and a second passageway comprising aligned inlet and outlet portions extending through said barrier plates transversely of said first passageway, said inlet and outlet portions being arranged on opposite sides of said first passageway and each extending into said first passageway, means for moving one of said first pair of contacts axially through said first passageway of said first device to extend said first arc, means for separatingsaid second pair of contacts to draw a second arc,. asecondarc-extinguishing device arranged in said chamber." and comprising aplurality of barrier plates iarrangdrtransversely of said-second arc, and a piston operatively connected to said first movable contact and movable therewith for causing a first flow of fluid through said second passageway across said first passageway of said first device to cool and extinguish said first are and for causing a second flow of fluid through said second 5 are to cool and extinguish said second arc.

References Cited in the file of this patent UNITED STATES PATENTS 10 Leeds May 20, 1947 Leeds et a1 July 20, 1948 Cushing June 10, 1952 Bartlett Aug. 5, 1952 Leeds Nov. 29, 1952 Friedrich et a1. Dec. 9, 1952 MacNeill et a1 Feb. 16, 1954 FOREIGN PATENTS Great Britain Apr. 12, 1949

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